Monday, July 25, 2016

What is checktable in teradata

"Checktable" is diagnostic tool provided by Teradata to identify inconsistencies and corruption in internal data structure of database objects in the system, it checks inconsistencies at table header, row identifier, secondary index and fallback table validity.

check table has 3 levels of checking

level 1: compares row count of subtable of primary data with subtable of fall back table for each cluster and reports the difference and also does row count comparison for base table and secondary index subtable.

level 2:  compares row identifier in various sub tables and report any inconsistency, It checks fallback & secondary index subtables for duplicate row id's , out of order rowids and incorrectly distributed rows,

level 3: compares the actual rows bytes by byte at secondary index, table header, rowid and fallback level. it is most resource consuming level and should be run in idle time.

check table can be run from superviser window in primary not of system using cnsterm 6 console.

command: start checktable will start the utility.

example check table command:
check all tables at level one with no error limit;

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